Ignition plug



T. R. ARDEN IGNITION PLUG March 14, 1950 2 Sheets-Sheet l Filed March 2, 1948 March 14, 195o T. R. ARDEN 2,500,395

IGNITION PLUG Filed March 2, 1948 2 Sheets-Sheet 2 Patented Mar. 14, 1950 IGNITION PLUG Thomas R. Arden, Danbury, Conn., assignor to Bard-Parker Company, Inc., Danbury, Conn., a. corporation of New York Application March 2, 1948, Serial No. 12,630

This invention relates to ignition plugs for internal combustion engines, and has particular reference to improvements in ignition plugs of the so-called glow type which are heated by the fuel charges which they ignite, as distinguished from ignition plugs of the well known so-called spark type.

One object of the invention is to provide an ignition plug of the glow type which embodies a simple, practical construction such that its heating or glow element may readily be heated electrically for engine starting purposes.

According to the invention, the plug body has therein a chamber which opens through the inner end of the plug body and in which the heating or glow element is disposed, whereby it is protected against flow over the same, and chilling by, the fuel charges to be ignited. In this connection, highest efliciency and most satisfactory operation of an engine is attained for any given fuel used for its operation if the engine has a compression space of definite size, best suiting it for operation by that particular fuel. It is very desirable, therefore, to provide means whereby the size of the compression space of an engine may be varied to adapt it for most highly emcient and satisfactoryoperation by any of a number of different fuels-which may be employed for its operation. The glow element-containing chamber of the present ignition plug constitutes, of course, part of the compression space of an engine with which'the plug is used. Accordingly, a special and important bject of the present invention is to provide an ignition plug embodying a simple, practical construction such that the sizeof its glow elementcontaining chamber may readily be varied to vary-the size of the compression space of the engine and thus adaptl the engine for most highly eiiicientA and satisfactory voperation by any given fuel which may be employed for its operation. 1"

In the foregoing connection another special and important object of the present invention is to provide for increasing the size of the compression space of an engine by increasing the length of the plug chamber and simultaneously moving the glow element outwardly in said chamber and, conversely, for decreasing the compression space oi the engine by reducing the length of the plug chamber and simultaneously moving the glow element inwardly in said cham ber. When a. fuel charge is fired, Ysome of the burnt gases remain in said plug chamber land act to retard entrance into the same'of fresh gases so that, depending upon the length of said chamber and therefore upon the amount of burnt gases that 'remain therein, the' time of ring of the engine is varied. This, in turn, enables fuels having different characteristics. Such 5 claims. (ol. 12s- 145) as ignition .temperature and speed of eombus-f tion, to be used and, for any given fuel used, enables firing at a time to secure maximum power. t t l Another specialand important object of the invention is to provide an ignition plug embodying a simple, practical construction such that the size of its glow element-containing chamber may be varied While the plug is applied to an engine and while the engine is operating, thereby to facilitate obtaining a proper adjustment of the size of said chamber and, hence, of the compression space of the engine.

With the foregoing and other objects in view, which will become more fully apparent as the nature of the invention is better understood, the same consists in an ignition plug embodying the novel features of construction, combination and arrangement of parts as are illustrated by way of example in the accompanying drawings and as will be hereinafter more fully described and claimed.

In the accompanying drawings, wherein like characters of reference denote corresponding parts in related views:

Figure 1 is a side elevation of an ignition plug constructed in accordance with one practical embodiment of the invention;

Figure 2 is a central, longitudinal section through the plug shown in Figure 1;

Figure 3 is a cross section on the line 3-3 of Figure 2;

Figures 4 and 5 are views similar to Figures 1 and 2, respectively, of an ignition plug constructedl in accordance with an alternative embodiment of the invention;

Figure 6 is an-end view of the plug shown in Figuresiand 5; and v v Figure 7 isa fragmentary elevation at `right angles to Figure 4fof the outer end portion of the plug shown in Figures 4 and 5.

Referring tofthe drawings in detail, rst wit particular reference to the embodiment of the invention illustrated in Figures 1 to 3, Il)r designates the plug bodywhich is exteriorly threaded at its inner end as indicated at to adapt it to be threaded into a plug-accommodating opening in an engine and which, in accordance with the invention, is provided with outer and inner axial bores I2 and I3, respectively, which open at their outer ends through the outer and the inner ends, respectively, of said plug body and are in communication with each other at their inner ends."`Vr `The inner bore I3 is smooth-walled and of 'smaller-diameter than the outer bore l2. On the ot'hler'hand, the outer bore l2 is threaded and has threaded'therein the enlarged outer end portion or head-l4 of a stem l5 which extends into and neatly, slidably fits the bore-i3.

The stem l5 is provided with anaxial `bore it the head I4 of said stem is provided with a chamber Il wherein an annular flange i8 on a rod I9 is clamped between a pair oi electrical insulating washers 29, 20.

The rod I9 includes an inner end portion 22# which is disposed in the bore IE and extends from the flange I8 substantially to the inner end 0i the stem I5, and an outer end portion 22 which` is threaded and extends beyond the outer end cf the plug body IIJ.

The washers 2|), 2U are confined in the head I4 of the stem I5, closely embrace the .rod I9, and clamp the flange I 8 of said rod between them. Thus, said rod is secured rigidly to said stem for movements with the latter. Moreover, said washers serve to hold both the rod I9 and its flange I8 coaxially disposed with respect to said. stem and spaced therefrom so that said rod is electrically insulated from said stem.

The heating or glow element 23'of the present plug is disposed beyond, but adjacent to, the inner end of the stem I and may be of any suitable form. Preferably, however, it comprises a length of suitable electrical resistance wire wound into helical form as shown, and having one end thereof welded or otherwise suitably connected to the inner end of said stem I5 and its other end welded or otherwise suitably connected to the inner end of the portion 2l of the rod I8.

Disposed against the outer end of the plug body Ill is a washer 24 of electrical `insulating material, while threaded on the outer end portion 22 of the rod I9 against said washer 24 is a suitable electrical terminal element 25.

When the plug is applied to an engine, the portion of the bore I3 between the inner end of the plug body II) and the inner end of the stem I5, together with the space between said stem and the inner end portion 2I of the rod I9, constitute a chamber a which is in communication with the compression space of the engine and, therefore, constitutes a part of the engine compression space. It follows, therefore, that by adjusting the stem l5 toward or from the inner end of the plug body, the size of the chamber a may be increased or reduced and that thereby the size of the engine compression space may be varied to adapt the engine for most highly efficient and satisfactory operation by any given fuel.

Since the head I4 of the stem l5 is threaded in the bore I2, said stem is, of course, by rotation thereof, adjustable into and from the bore l3^to vary the size of the chamber a. In this connection, to adjust said stem, the terminal element l25 may simply be removed from the portion 22 of the rod I!! and said portion of said rod may be engaged and rotated in any suitable manner to rotate the stem I5. Or, the washer 24 also may be removed and a suitable implement may be engaged in any suitablefmanner directly with the head I4 to rotate said stem. If desired, a nut 26 may be screwed into the bore I2 against the head. I4 to lock the stem I5` in any desired adjusted position thereof.

The bore I3 is of sufficient length to accommodate the glow element 23 as well. as a considerable portion of the stem I5 so as to permit all necessary variation in the size of the chamber a and, hence, in the size of the compression space of an engine with which the plug is used, while maintaining the glow element 23protectively confined in the chamber a. In this connection it is apparent that since the glow element 23 is carried by the stem l5 and the rod I9, it is movable outwardly and inwardly in the chamber a with said stem and said rod as the latter are adjusted to increase and to decrease the length of said chamber. This is an important feature of the it plug for the reason that when a fuel e is fired, some of the burnt gases remain in the chamber a and act to retard entrance into the same of fresh gases so that, depending upon the length of said chamber and the consequent amount of burnt gases that remain therein, the time required for fresh gases to reach the glow element 23 and to be ignited is varied with consequent varying of the time of firing of the engine. In otherU words, the time of 'Firing of the engine is varied not only by varying the size of the compression space of the engine as a result of varying the length of the chamber a, but by varying the position of the glow element 23 in said chamber. This, obviously, enables fuels having different characteristics, such as different ignition temperatures and speeds of combustion, to be used and, for any given fuel used, enables ring to be effected at the proper time to secure maximum power therefrom.

The plug body I is electrically grounded through an engine upon which the plug used. Accordingly, if one side of a source of current is grounded to the engine and the other side thereof is connected to the terminal element 25, a circuit will be established through the glow element 23 and the latter will be electrically heated for starting purposes. After the engine has started, the heat of combustion in its compression space will, of course, maintain the glow element heated so that electrical heating of said element may be discontinued.

Obviously, by removing the terminal element Z5 and the washer 24, the electric circuit may be established through the rod I9 and adjustment of the stem I5 may advantageously be effected while the engine is running. After the proper adjustment of the stem I5 has been eifected, the washer 24 and the terminal element 25 may be applied and said terminal element may, i1' desired, be relied upon in lieu of the lock nut 26 to maintain the adjustment.

Referring now particularly to the plug of alternative form shown in Figures 4 to 7 of the drawings, I5 designates the plug body which is exteriorly threaded at its inner end, as indicated at iI, to adapt it to be threaded into a plugaccommodating opening an engine, and which, in accordance with the invention, is provided with outer and inner axial bores I2' and I3', respectively, which open at their outer ends through the outer and the inner ends, respectively, of the plug body and are in communication with each other at their inner ends. The bore I3' is of smaller diameter than the bore I2 and both bores are smooth-walled. In the bore I2' is disposed an enlarged outer end portion or head I4' of a stem I5' which extends into and neatly, slidably fits the bore I 3'. The head I4 slidably fits the bore I2' and is suitably splined or keyed to the plug body In', as indicated at 21, so that it and the stem I5 are held against rotation relative to said plug body.

The stem I5 is provided with an axial bore I6 and the head I4 of said stem provided with chamber Il wherein an annular flange I8 on a rod I9' is clamped between a pair of electrical insulating washers 2G', 2G.

The .rod IQ includes an inner end portion 2| which is disposed in the bore I 5 and extends substantially to the inner end of the stem IE', and an outer end portion 22 which is threaded'and extends beyond the outer end of the plug body l0'. e

The washers 20 are confined the-head I4', embrace the rod I9' and clamp the-flange I8 of said rod between them. Thus, said "rodfand said stem are secured rigidly togethersofgffthat longitudinal adjustments of said rod effec tudinal adjustments of said stem. Moreov washers serve to hold both the rod [Sifyy ,I fiange I8' coaxially disposed with respect to said stem and spaced therefrom so that saidv rod is electrically insulated from said stem. Y j;

The heating or glow element 23 may be ofthe same form as the heating or glow element-,1 l23 of the Figures 1 to 3 form oi' the invention,A a be mounted with referenceto the stein |,5"and the inner end portion 2| of the rod I S'iin the same manner as the heating or glow element 23 is mounted with reference to the stem lvgfand the inner end portion 2l ol the rod I9.

At the outer end of the plug body I0', in axial alinement with the bores I2 and I3', i's anannular ange 28 which is exteriorly threaded :and has threaded thereon a collar 29 of electrical insulating material. This collar also is,Y exteriorly threaded and has threaded thereOn-aterminal element which may be of any suitable form, but which is transversely slotted, as. indicated at 30, to accommodate a nut 3 l. i

The nut 3| is threaded on the outer end por- Because the nut 3| is disposed in the slot 30,

it is held against longitudinal movementrelative to the terminal element 25' or, in other-words, is swiveled with respect to said terminal element. The stem l5 and the rod I9' are, as aforesaid, held against rotation due to the splined' connection 21, between the head I4 of said stem and the plug body l0. Consequently, simply by rotating the nut 3l, the rod I9 and the stem I5' may be longitudinally adjusted to vary thesize of the chamber a', corresponding to the chamber a of the Figures 1 to 3 form of the invention, for, of course, the same purpose as the size of the chamber ais varied.

The terminal element 25 is provided with an axial bore 32 to accommodate the Aouter end of the portion 22' of the rod I9', but is electrically connected to said rod through the nut 3l. On the other hand, the collar 29 servestoelectrically insulate the terminal element 25;?y andgthe nut 3l Q from the plug body Ill'. Accordingly,fif one side of a source of current is connectedv to the plug body I0' and the other side thereof "isV connected to the terminal element 25', a' circuit will be completed through the heating` or-fglow element 23' and the same will become electrically heated fm engine starting purposes. Atte has started, the heat of fuel charges: ignited by the glow element will maintain the latter hot and electrical heating of said element `may be discontinued.

A particular advantage of the Figures 4 to 7 form of the invention is that there is no need of disturbing the plug assembly ini-anyway in order to adjust the size of the chamberzf, since the nut 3| always is exposed for ready 4manipulation to accomplish that purpose. .f

From the foregoing description `considered in connection with the accompanying drawings, it is believed that the construction and operation of the present ignition plug will be clearly underinvention, as defined in the appended claims.

I claim:

1. An ignition plug comprising a plug body having a bore opening through its inner end, a stem extending into said bore from its outer end, means holding said stem against rotation relative to said plug body, a. rod extending through said stem and electrically insulated therefrom l'and xed with respect thereto, a terminal element mountedon the outer end portion of said plug body and electrically insulated therefrom, a nut swiveled in said terminal element and threaded on said rod whereby it is effective by rotation to adjust said rod and stem longitudinally to vary the size of the compression space of an engine with which the plug is used, said nut serving to connect said rod electrically with said terminal element, and a glow element oi electrical resistance material disposed adjacent to the inner end of said stem and connected at spaced points to said stem and said rod.

2. An ignition plug comprising a plug body having inner and outer axially alined bores opening through its inner and its outer ends, respectively, said outer bore being of great diameter than said inner bore and being in communication with the latter, a stem extending into said inner bore from the outer end thereof and having a head disposed in said outer end thereof and having a head disposed in said outer bore, said stem having an axial bore and said head having a chamber, an electrical conductor including a portion disposed in said stem and a flange disposed in said chamber, washers of electrical insulating material disposed in said chamber and cooperating with said head and said ange to electrically insulate said conductor from and to rigidly fasten the same to said stem, means for adjusting said stem and its head longitudinally relative to said plug body to vary the distance between the inner end of said stem and the inner end of said plug body, thus to vary the size of the compression space of an engine with which the plug is used, and a glow element of electrical resistance material disposed in the inner end portion of said inner bore and connected at spaced points to said conductor and said stem.

3. An ignition plug comprising a plug body having inner and outer axially alined communicating bores opening through its inner and its outer ends, respectively, a stem extending into said inner bore from the outer end thereof and having a head threaded in said outer bore whereby rotationiof said head and stem is effective to adjust said head and stem longitudinally relative to said plug body to vary the distance between the inner ends `of said stem and said plug body thus to vary the size of the compression space of an engine with which the plug is used, an electrical conductor extending through and insulated from and fixed rigidly to said stem and head, and a glow element of electrical insulating material disposed in the inner end portion of said inner bore and connected 'at spaced points to said conductor and said stem.

4. An ignition plug asset forth in claim 3 in which the conductor includes a threaded portion extending through the outer bore beyond the outer end of the plug body, and in which an elecamm trlcal` terminal element is threaded-on said'stem in closing relationship to the outer end of the outer bore. l -1 5. An ignition plug `comprisinga plug body having inner and outeriaxially alined communi eating bores opening through its inner `and `its outer ends, respectively, a. stem extending into said inner bore from the outer end thereohan electrical conductor extending throughfand xed to and insulated from said stem, said conductor including a threaded outer end portion, vav nut swiveled with respect to said plug bodyand having threaded engagement with the outer end portion of said conductor for adjusting the latter and said stern longitudinally relative to saidplug body to vary the distanee between the inner ends of said stem and said plug body thus to vary the sizeof the compression space of an engine with which the plug is used, and a glowelement of Number` electrical insulating material disposed in the inner end portion of said inner bore and conmeetedr at spaced points to said conductor and said stem. l

THOMAS R. ARDEN.

nE'FERENCES CITED The following references are of record in the -le of this patent:

'UNITED STATES PATENTS 

